Render 2D cross sections of 3D Objects
That can be done using shader driven by the current frame.

The node settings:

The generated texture coordinates is between 0 and 1.
Value nodes: one is driven by the current frame, the other is the amount of frames (here 100).
We then test if the model part is between frame and frame + 1 / number of frames.
If yes, emission surface and emission volume. If not transparent.
The driver is based on the scene and its current frame:

All is done with Cycles.
Depending on the camera settings, that can be perspective or orthographique (so constant size).